In a wireless propagation path for mobile communication, a bit error is generated due to, for example, thermal noise in a reception device, resulting in deterioration of communication quality. In recent years, technology for compensating for the deterioration of the communication quality using an error correction code has been known. However, a reception device using such technology may not correctly decode data. Accordingly, performing of retransmission control (referred to as automatic retransmission control or ARQ (Automatic Repeat reQuest)) to transmit the same data again when a reception device cannot correctly decode data is known.
Retransmission controls include non-adaptive ARQ and adaptive ARQ. In the non-adaptive ARQ, the same transmission scheme is used for retransmission data and initial transmission data. For example, in technology with non-adaptive ARQ, a chase combining method is used. Technology described in Patent Literature 1 is known as technology with adaptive ARQ.
Meanwhile, turbo codes capable of achieving a characteristic close to a Shannon limit are known as error correction codes (see Non-Patent Literature 1). In the turbo codes, recursive systematic convolutional (RSC) codes of a plurality of component encoders are connected in parallel.
In recent communication technology, a turbo equalizer in which an iterative decoding scheme based on a turbo principle used in a turbo code decoding process is applied to a MAP (Maximum A Posteriori Probability) detector and a decoding unit is known. As such technology, technology described in Patent Literature 2 is known.